# CVE-2025-27915

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.

- Page: https://www.vulneraibility.com/cve/CVE-2025-27915
- CVSS: 5.4
- Known exploited: yes, in CISA KEV since 2025-10-07; CISA due date 2025-10-28
- EPSS: 4.06%
- Detection templates only, no public exploit found: 1 Nuclei template
- CISA SSVC: exploitation active, automatable no, technical impact total (assessed 2025-10-07)
- Weakness: CWE-79
- Published: 2025-03-12

## Affected

- synacor:zimbra_collaboration_suite

## References

- [other] https://wiki.zimbra.com/wiki/Security_Center
- [other] https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes
- [other] https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes
- [other] https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes
- [other] https://strikeready.com/blog/0day-ics-attack-in-the-wild/
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.